Domestic and industrial wipers are often used to quickly absorb both polar liquids (e.g., water and alcohols) and nonpolar liquids (e.g., oil). The wipers must have a sufficient absorption capacity to hold the liquid within the wiper structure until it is desired to remove the liquid by pressure, e.g., wringing. In addition, the wipers must also possess good physical strength and abrasion resistance to withstand the tearing, stretching and abrading forces often applied during use. Moreover, the wipers should also be soft to the touch.
In the past, nonwoven fabrics, such as meltblown nonwoven webs, have been widely used as wipers. Meltblown nonwoven webs possess an interfiber capillary structure that is suitable for absorbing and retaining liquid. However, meltblown nonwoven webs sometimes lack the requisite physical properties for use as a heavy-duty wiper, e.g., tear strength and abrasion resistance. Consequently, meltblown nonwoven webs are typically laminated to a support layer, e.g., a nonwoven web, which may not be desirable for use on abrasive or rough surfaces. Spunbond webs contain thicker and stronger fibers than meltblown nonwoven webs and may provide good physical properties, such as tear strength and abrasion resistance. However, spunbond webs sometimes lack fine interfiber capillary structures that enhance the adsorption characteristics of the wiper. Furthermore, spunbond webs often contain bond points that may inhibit the flow or transfer of liquid within the nonwoven webs.
In response to these and other problems, nonwoven composite fabrics were developed in which pulp fibers were hydroentangled with a nonwoven layer of substantially continuous filaments. Many of these fabrics possessed good levels of strength, but often exhibited inadequate softness and handfeel. For example, hydroentanglement relies on high water volumes and pressures to entangle the fibers. Residual water may be removed through a series of drying cans. However, the high water pressures and the relatively high temperature of the drying cans essentially compresses or compacts the fibers into a stiff structure. Thus, techniques were developed in an attempt to soften nonwoven composite fabrics without reducing strength to a significant extent. One such technique is described in U.S. Pat. No. 6,103,061 to Anderson, et al., which is incorporated herein in its entirety by reference thereto for all purposes. Anderson, et al. is directed to a nonwoven composite fabric that is subjected to mechanical softening, such as creping. Other attempts to soften composite materials included the addition of chemical agents, calendaring, and embossing. Despite these improvements, however, nonwoven composite fabrics still lack the level of softness and handfeel required to give them a “clothlike” feel.
As such, a need remains for a fabric that is strong, soft, and also exhibits good absorption properties for use in a wide variety of wiper applications.